This invention relates to telephone communications systems and particularly to systems for monitoring telephone circuits.
In the monitoring of telephone circuits, various control signals including addressing signals are detected and decoded. Thereby, the performance and/or efficiency of the telephone equipment and the network in which they are connected can be determined and faulty or improper operation identified for the purpose of improvement or correction. A description of a monitoring system for telephone lines used as a "Line Usage Measuring Circuit" is in the U.S. Pat. No. 3,829,618.
In prior art monitoring systems, the monitoring equipment detects when an observed telephone line is seized or an off-hook condition occurs and connects to the line for the purpose of obtaining the various control signals that occur, whereby the disposition of the call can be determined. When the disposition is determined, the monitoring equipment is freed to connect to the next seized line. A separate equipment of that type is needed for monitoring each of the telephone lines that are seized at any time, and, since the equipments can be costly, such systems have limited effectiveness.